"One spell," Madison told Sierra sternly. "That's all you get. And you should feel grateful you're even getting that."

Sierra pouted up at her former babysitting charge, hoping her pitiful expression might change her mind, but Madison was immune, even while Sierra's body was four years old, and standing there with her thick Pampers peeking out from under her nightshirt. "But it's been so wong since you've wet me do anything! What if I can't get it wight the fiwst time?"

"I'd be more than happy to cast the spell for you," the now-older girl offered. "In fact, that might be a very good idea."

"I can do it!" Sierra quickly changed her mind.

"And don't try anything mean," Madison warned. "It isn't nice for magic users to bully regular people with their abilities. And besides, it's her birthday! You know this is supposed to be something nice, so don't make me punish you for being a naughty girl over this."

Sierra bit her tongue, knowing better than to explain how she was definitely not the bully here, and that anything she did would be perfectly justified. Even though Madison had never even been through any magic schooling, and Sierra had graduated, or pretty much anyway, she was always trying to teach Sierra things, as if she didn't already know even better than her. Lately, her lessons seemed to focus a lot on using magic responsibly, especially when it came to Muggles.

However, what Madison didn't know wouldn't hurt her, and despite acting like a know-it-all, the truth was that she didn't know what a lot of spells did. It had been her subconscious desires, and latent magical abilities, that had allowed her to use Sierra's wand when she was a kid, and she was still mostly doing the same thing. She was powerful enough that she was still able to accomplish quite a bit, but when it came to spells, unless she'd seen Sierra use it before, she was clueless.

Sierra could cast just about anything, assuming she could say the incantation correctly with her childish lisp, but the single spell thing made it tricky. She could try to do something to Madison, but she wasn't even sure if it would work. Her wand seemed to have taken to the girl more than it ever had to her, not to mention that she was sure Madison would realize something was up the moment Sierra pointed the wand in her direction. Putting a spell directly on herself probably wouldn't work out, either.

Madison probably expected, and wanted, Sierra to conjure up some kind of magical toy. She had offered to take Sierra shopping, but Sierra had insisted she could make something better, until finally Madison had given in. She hadn't expected that, though, so she didn't have a real plan for what to do once she got to this point. Anything she made, Madison would probably test out before they wrapped it up, so anything too obviously malicious would just give her plan away. She needed something a little sneakier.

"All right, I guess if you don't have anything planned, we can try to find time tomorrow to go shopping. I wish you would have just admitted earlier, you know we already have too much to get done tomorrow," Madison shook her head, reaching for the wand. "It's getting way past your bedtime anyway."

"No, I can do it!" Sierra insisted. She bit her bottom lip, squirming as she tried to think harder and faster, trying not to pay attention to the trickle of warmth making its way into her diaper as she concentrated. Finally, she waved her wand, letting out a long stream of words, trying to tie together several spells into one and hoping Madison wouldn't figure it out.

In a puff of magic, one of the pillows on the couch transformed, turning itself into an adorable pink plush bunny. It turned its stuffed head, looking around a little in confusion and wiggling its ears. "Oh, that's perfect!" Madison smiled, taking the wand back and sitting down next to the moving toy. "I'm sure she'll love this! Good job!" She reached over, ruffling Sierra's hair. "We'll get it wrapped up tomorrow, okay? Right now, we need to get you changed and to bed." Sierra blushed, realizing Madison had noticed her little accident. "That's definitely something you're going to have to work on," Madison teased her. "It's going to get pretty messy if you're wetting yourself every time you try to cast a spell."

"I wooon't!" Sierra pouted. "It was just an accident!" She sulked as Madison took her hand and led her back to her bedroom, putting a fresh nighttime diaper on her and tucking her into her crib. As she squirmed under her blankets, though, she couldn't help but smile. This time, she was really going to teach Zoe a lesson!

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Sierra yawned and stretched, happily nuzzling on her pacifier for a moment, wrinkling her nose as the squishy feeling in her diaper. She squirmed a little, whimpering softly, then gasped as she finally woke up enough to realize what was happening. She'd messed her diaper in her sleep!

Her cheeks were burning as she opened her eyes, hardly able to believe it. Madison usually let her use the potty for that, unless she was being punished, because she still believed Sierra when she said she could control herself that way. Doing it in her sleep was definitely not going to help her case!

After a few moments, she remembered that she hadn't gone to sleep with her pacifier in, either. She frowned, trying to remember if it had even been in the crib with her when she fell asleep. Surely it must have been, but she couldn't remember it.

The longer she was awake, the more things began to feel wrong. She sat up, looking around through her crib bars, but the room didn't look quite the same beyond them. It looked familiar, but it definitely wasn't the one she looked at every morning. It felt like she was getting a much higher perspective on it than usual, though, so she almost thought that was it. Glancing down at herself, it was obvious she wasn't a four year old anymore.

Could the regression spell have finally worn off? Had Madison decided she was mature enough to be an adult again? Was it some kind of natural, but delayed, reaction to finally being allowed to use her wand again?

When she looked at herself again, however, it started to become obvious that it wasn't as simple as that. As much as she would have liked to believe otherwise, her body had never been quite as developed as this one. And, again, though it seemed familiar, the longer she looked, the more certain she was that it wasn't her own.

That was when she noticed the bunny, the one she'd made for Zoe the night before, sleeping in the corner of the crib, its ears twitching every now and then. She gasped, scrambling forward, trying to make sure it was, in fact, the same one, but of course it was. The spell must have been too powerful, she realized as she stared at it. She wanted to make sure it went right to Zoe once it was opened at the party, but it had somehow gotten out of the house and found her early, activating the other part of the spell.

"Oh, no," she sighed, looking around the room again, recognizing it this time right away. She was in Zoe's body, and Zoe was in hers.

"Good morning, birthday girl!" Lilly exclaimed, opening the door to the nursery and stepping in. Sierra wasn't sure what to say, so she just sat there, stunned, as Zoe's mommy walked over to her, giving her diaper a check. "Uh-oh, looks like someone had a busy night! Come on, let's get you nice and clean, okay?"

Sierra nodded, letting Lilly help her out of the crib once she'd lowered the side, and was led over to the changing table. She squirmed as Lilly untaped her diaper and started to wipe her clean, wondering what was happening over at her own house right now. Was Zoe up yet? Had she figured out what was going on, or would her younger body, and Madison being there to get her up and ready for the day just confuse her, and make Madison either wonder what was wrong with Sierra, or figure out that Sierra's little spell the night before hadn't been quite so innocent.

This wasn't what she'd intended to do! Well, it was, but not like this! She wanted Zoe to open her present, and have the bunny jump out of it and into her arms and trigger the change then. That way, Zoe could really see just what it was like to be Sierra for a little while, until she touched the bunny again and they switched back. Maybe then, after seeing how hard it was being stuck in a toddler's body, and with Madison always there being strict, she would stop picking on her so much!

Obviously that would have been disorienting for her, too, but it probably wouldn't have been as bad as just waking up in Sierra's body, with no way of knowing why or how it was happening! There was really nothing Sierra could do about it now either. Her wand was off in another house altogether, and even if she had it, she didn't think she could use it! When it came to switching bodies like this, she was pretty sure the magical talent would stay with her physical body, which just made her glad that there was no way Madison would let her use the wand again anytime soon, because who knew what Zoe would do with it!

"You're quiet today!" Lilly observed, tickling Sierra's tummy and making her giggle. "Are you nervous about your party?"

"Uh, yeah," Sierra nodded, unsure how else to answer.

"Aww, it'll be fine! You'll have lots of fun!" Lilly promised. "It's a good thing I have the perfect antidote for tummy butterflies!"

She led Zoe, still in her nightshirt, to the dining room, helping her up onto her highchair before plopping down a plate of chocolate chip pancakes in front of her. "Eat up, sweetie!" Lilly told her, kissing her on the forehead. "There's more where that came from if you want them!"

Sierra picked up her plastic fork hesitantly. It felt a little wrong, taking over this part of Zoe's birthday celebration. She knew that Madison would, as always, insist on a healthy breakfast, which meant gross oatmeal and some fruit. Sierra had, in the past, made it quite clear how much she disliked the oatmeal, though she'd learned to be quiet about it, since complaining usually just earned her a second helping and a lecture on how Madison somehow thought she knew more about what to feed a growing girl than Sierra.

She couldn't imagine that Zoe would find the oatmeal any tastier than she did, and she didn't know not to complain. As Sierra nibbled on her yummy, syrup drenched pancake, she thought of Zoe sitting in Sierra's highchair, eating her first spoonful of the gooey gunk and gagging, maybe even pushing the bowl away and insisting on something else. She might even wind up pushing the bowl off the tray altogether, which would definitely get her a spanking, although maybe not right away, since Madison was bound to be in a rush today to get all her errands done before the party.

She hated to admit it, but the image made her smile a little. After all, it was Zoe's fault that Sierra was stuck as a four year old, and in diapers, at the moment, since she was the one who had insisted Sierra visit Santa's workshop. At least before that, Sierra was old enough to go to school, and was slowly earning her way back to big girl panties. It might be a little mean to do it on her birthday, but Zoe did deserve to know what it was like.

It was definitely going to be a busy day, too. Madison had promised to help with decorating for Zoe's party, but she'd kept putting off getting the decorations, or cake, or anything else. She really only had herself to blame, but Zoe was going to find herself all dolled up in her diaper and a party dress and being dragged from store to store, where everyone was bound to treat her like the toddler she was, at least physically. If she acted too bratty, which seemed likely considering her usual self, and how strict Madison was, she might even get dropped off at the mall daycare while Madison finished up her shopping!

Sierra always did her best to avoid that. Regular daycare was bad enough, but at least there the teachers did their best to keep order. The few times she'd gone to the one at the mall, it had been chaos! She shivered a little just thinking about it. The bigger kids always liked to pick on her for some reason, and if she tried to defend herself, it seemed like it was always just as Madison was coming to pick her up, and she got in trouble for not handling her problems like the big girl she really was, as if reason would work on the brats there!

Maybe that would be good for Zoe, though, and show her that it wasn't nice to pick on somebody smaller than her. Besides, once that was all done, she and Madison ought to get here before most of the other party guests, so Sierra could switch them back, and Zoe could enjoy her party as herself.

Before that could happen, though, Sierra had to finish her pancakes, then go have a nice, relaxing bubble bath before getting a fresh diaper and sat down in her nursery with her toys. Sierra didn't really get how she could have so much fun with such childish things, but she always did, and since she didn't want to make Lilly suspicious, she had to do the same. If nothing else, it was a lot of fun to watch the bunny she'd made hop around! It really did work very well, much better than she would have expected, considering how rusty she was sure her magic would be by now. Maybe all that practice with the toy wand Santa had given her really was paying off.

As she sat there, stacking blocks and having more fun with that than she would have liked to admit, she began to have another worry. Obviously, Zoe didn't know what was going on. Madison might write some of it off as Sierra playing pretend or something, or trying to get out of having to go shopping, or to the party, but what if Zoe just came out and told her who she was? Would Madison believe her, and work out what had happened? After her warnings the night before, Sierra doubted she would go easy on her once she had her and Zoe back in their right bodies.

She half expected Madison to come storming through the door, even earlier than expected, to get on that. When Lilly came to fetch her, telling her that her guests were starting to arrive, she felt nervous, glancing around the room for the bunny, thinking that it would be better to switch back as soon as possible, but the toy had apparently hopped off somewhere else! Frantically, she started to look for it, but Lilly grabbed her hand and started pulling her away, telling her she needed to entertain her guests.

Much to Sierra's surprise, it wasn't Madison and Zoe in her own body waiting for her in the living room, which was still undecorated. It was a girl Sierra didn't recognize, probably in her early twenties. She was about medium height, and quite cute, although Sierra found it difficult to take her eyes off of the girl's ears. Or, rather, her second set of ears, which were a pair of bunny ears.

"Happy birthday, Zoe!" the girl grinned, giving her a big hug.

"Thanks!" Sierra responded, finding it hard not to give in to the girl's enthusiasm, even if she wasn't sure who she was. "Thanks for coming to my party!"

It was much easier to play now that there was somebody else to play with her, even if Sierra felt awkward, not really sure of the girl's name, or what was going on with the bunny ears. They were big, and looked very soft and fluffy, but she didn't dare try to touch them, since she wasn't sure how the girl would react. She had a feeling Zoe would know, which made her even more hesitant in case the girl had already told Zoe not to do it.

Before long, the other guests started to arrive. There was Abby, of course, with little Laura trailing along behind. Sierra hadn't seen much of either of them since Madison had made her change them back to their real ages and apologize after their time at summer camp, so she felt pretty awkward seeing them now, although it helped knowing that they thought she was Zoe.

She wasn't sure if Abby even noticed. "I got you some fun new toys," she exclaimed, with a tone of voice that made Sierra feel pretty sure these were a lot different from the toys she and the bunny girl had just been playing with. "Want to find somebody to try them on?"

"N-Not right now," Sierra said. "B-But thank you!" Normally, she was the one who they would have tested the toys on, but she wasn't there. Or, at least, her body wasn't yet, which was starting to make her nervous. What was going on?

In "Sierra"'s absence, Abby seemed to be eyeing Laura, who was biting her bottom lip nervously, until Sierra turned her down. "Are you feeling okay?" she asked at first, then shrugged. "Well, we can do it later, then!"

"S-Sure," Sierra nodded.

Some more people showed up, a lot of whom Sierra didn't really know. Elizabeth came, standing off to the side looking elegant as she watched the others play with something of a bemused expression. She was looking prim and proper and elegant as always. Sometimes Sierra wondered why she hung out with all these babies.

But there was no sign of Zoe! Where could she be? Sierra was starting to feel worried. What had Zoe done? Could she have done what Sierra herself had been unable to do, and get ahold of her wand for more than one supervised spell? Who knew what she'd be able to do with that?! She actually felt a little bad for Madison, if that was the case.

Finally, after it seemed like everyone else was there, and milling around in a room with no decorations, and no cake, the front door burst open again, and in stormed Madison, carrying a large cake. Sierra froze, certain that she knew the truth and that she was coming for her, but instead she turned back and rolled her eyes, stomping back outside and returning, half-dragging "Sierra", her little arms full of bags, with her.

"Is that Sierra?" Abby asked. Sierra nodded, biting her bottom lip nervously. "What happened to her?"

"She's so cute!" Laura exclaimed. Sierra had to admit that was true, looking at her body from the outside. Just as she'd expected, Madison had put her in her lacey pink party dress, and the bottom of her diaper was quite visible under it.

"I'm so sorry!" Madison shook her head, balancing the cake and pulling Zoe along as she hurried over to Lilly. "I don't know what's gotten into Sierra today, but she has been a terror! If I hadn't promised to bring you all this stuff, I wouldn't have even let her come!"

"It's all right, you know how little ones can be," Lilly smiled. "I'm sure everyone would love to help decorate anyway!"

Madison pried the bags away from Zoe, who was looking around at all the guests who had shown up, and began passing out streamers and balloons. After a moment, Zoe spotted Sierra, staring her straight in the eyes for a long moment before sticking her tongue out.

Even knowing that, physically, she was in the bigger body now, Sierra couldn't help feeling nervous. It sounded like Zoe had already gotten into plenty of trouble, but she had the power to get Sierra into even more trouble if she left things the way they were. "I-I'll be right back," she told the people closest to her before scurrying back to the nursery. She needed to set this right as soon as possible!

But the bunny was nowhere to be seen! Sierra began frantically searching through Zoe's room, pulling toys out of the toy box, but it was nowhere to be seen!

"There you are!" Lilly said. "Silly girl, I bet there are lots of new toys for you to play with out in your packages! Come on, the cake is ready, and then the birthday girl has presents to open!"

"I-I just want..." Sierra protested.

"Everybody's waiting!" Lilly told her, sounding a little more stern. "Your toys will be here when the party is over, I promise."

Sierra felt even more awkward about the whole situation now as she was taken back to the living room, which was decorated somewhat haphazardly, and made to sit and listen to everyone, including the real birthday girl, sing happy birthday to her. She really hadn't meant to steal this moment from Zoe!

Madison hadn't let Zoe get too far from her, and Sierra almost expected her not to let her have any cake if she'd been acting as bad as Madison had said. That really would have made Sierra feel bad, since it was Zoe's cake, after all, but after serving everyone else, she got a small slice for Zoe. Zoe smiled at her sweetly and thanked her, then promptly threw the cake on the floor.

"Sierra!" Madison scolded her. Sierra jumped reflexively before remembering Madison didn't know who she was at the moment.

"It was an accident!" Zoe said. "I'm sowwy! Can I have some mowe?"

Madison glared at her, but Lilly stepped in. "It's all right, it can be hard to keep ahold of plates sometimes, huh?" She smiled down at Zoe. "I'll get it all cleaned up! Go on, it isn't a party without cake!"

Madison reluctantly sliced another piece of cake, and Zoe took another couple bites before tipping her plate again. This time, she let it fall towards herself, then "caught" it, smashing it against the front of her party dress, letting the excess crumbs tumble to the floor, where Madison had just finished cleaning up the first slice.

"Sierra!" Sierra jumped again, but Zoe just giggled.

"Sowwy!" she said, making it obvious she wasn't at all.

"Why are you acting this way?" Madison demanded, obviously trying to keep her voice down, but she was still talking loud enough for Sierra to hear. "You've been doing so well lately, but now you're back to acting like a baby!"

"I wike being a baby!" Zoe exclaimed. With that, she began to squat down. Sierra let out a little gasp, her stomach churning as she realized what was about to happen. Zoe looked straight at her and giggled, then gave a little push. It was very strange standing there, watching her own body mess its diaper, which quickly began to bulge and sag under her.

"Sierra!" Madison shook her head. "You promised me you didn't have to do that! I didn't bring a change with me!"

"I can't hewp it!" Zoe giggled. "I just wove going poopie in my Pampews!" She plopped down on the floor, squirming in place, obviously trying to make her diaper even messier. Sierra's cheeks burned as she watched herself do that, knowing that everyone else was seeing it, too, and hearing her own voice say those things as if she really meant it. Zoe caught Sierra's eye again, smirking.

Obviously, this whole switch hadn't bothered her too much at all! In fact, she might even be enjoying it, at least when it came to making it look like Sierra was doing and admitting to all this stuff! It wasn't fair! Sierra glared at her, trying to bear down herself and copy the girl, but Zoe had obviously already emptied her bowels the night before. Instead, she started to pee, pulling up the hem of her skirt so everyone could see the star designs on her diaper fade.

"Well, I-I love peeing my diaper!" she exclaimed, forcing herself to speak loudly, reminding herself that everyone thought it was Zoe doing this. "I'm just a big baby, I can barely even help it!"

"I think we all know that," the girl with the bunny ears giggled.

Sierra blushed again. That was true. Zoe had never really been shy about any of this, so there wasn't much that she could do to embarrass the girl. "Yeah, well, I really do!" she pouted, accepting her defeat. This really was not working out the way she'd expected at all!

"I think we'd better go," Madison shook her head, trying to scrape off most of the cake from Zoe's dress with a napkin. "I don't know what's gotten into her, but she definitely needs a change."

"I don't think anyone will mind too much, but if you think it's best," Lilly shrugged.

Sierra's eyes widened a little at that. They couldn't go now! She wasn't sure when she had planned to come visit Zoe next, and without Zoe there to touch the bunny toy, wherever that had gone to, the spell couldn't be reversed! It was supposed to be a short term thing, probably just a few minutes, maybe an hour. It had already gone on longer than she expected, but who knew what would happen if it stretched on for days!

She tried to slip back to Zoe's bedroom, but Abby caught her. "Come on, it's time to see the new toys I got for you," she said, pulling Sierra back towards the main group.

"B-But I..." Sierra protested, only to be sat down in a big chair, presents piled around her. She looked towards the front door desperately, seeing Madison getting Zoe ready to go, still apologizing to Lilly. Zoe glanced back, looking a little envious as she saw the pile of presents, then stuck her tongue out at Sierra again. Sierra squirmed in the chair, wondering what further mischief the girl had planned for her, to get her into even more trouble!

"I don't wanna open presents right now," Sierra whined.

"Maybe she really is sick," Laura said, a little nervously.

"I could take her temperature," Abby giggled.

"No, I just need to..." Sierra shook her head, watching as Zoe, dress a mess of pink icing and cake crumbs, diaper drooping heavily between her legs, started to be pushed out the door, taking with her the last chance of putting this right for quite a while.

Then, just in the nick of time, Zoe stopped and turned, her eyes opening wide in surprise. "Bunny!" she exclaimed happily, pulling her way out of Madison's grip and dashing away. Sierra watched her kneel down, and then, in a sudden, disorienting flash, she was across the room, kneeling down and petting the toy bunny she'd made the night before. Sierra whimpered, squirming in the full diaper she was now wearing instead of just seeing, but still very relieved to be in her own body.

"How did that get here?" Madison wondered out loud. "Sierra made that for Zoe last night, but this morning we couldn't find it! I don't know how it got here. Well, you might as well give it to her before we head home. Go on!"

Sierra nodded, chewing her bottom lip as she scooped up the plush toy and made her way across the room, blushing as she stepped past everyone, knowing they'd just seen "her" acting like a bratty toddler. She held the squirming toy up to Zoe, cheeks bright red as she stuttered, "H-Happy b-biwthday, Zoe."

Zoe smirked down at her for a long moment before patting her on the head and taking the present. "Thanks, 'tinkie tot," she said. "You should really be a better little girl for your Mommy," she continued after a moment. "Acting all naughty like that doesn't do anybody any good."

Sierra glared at her, wanting to tell everybody the truth, about how it hadn't been her doing all of that. She wasn't sure how many people would believe her, although as she'd passed by the girl with the bunny ears, she could have sworn she felt some magic coming off of her, now that she was back in her own body and had her own magic back. She wasn't sure what the story with that was, but she was curious to find out when she had a chance. Before she could decide if it was worth trying to explain things, Madison was behind her, making her say goodbye and pulling her out to the car, where she buckled Sierra into her car seat, shaking her head.

"Don't think I've forgotten about earlier today either, young lady," she lectured as they started to make their way back home. "I know I didn't have time to punish you properly then, but that doesn't mean you got away with any of it! You are in for quite the punishment tonight! If you like those messy diapers so much, maybe you'd better stay in them for your corner time. Will you still love them after that? I believe I owe you a spanking after that as well, and even though it seems like you emptied yourself out pretty well, you're still supposed to get an enema, so I suppose we'll clean out that last little bit. And you've got some lines to do, too, don't you? And we'd better not forget..."

Sierra squirmed uncomfortably in her car seat, her bladder dribbling nervously into her diaper as the list went on. What had Zoe done?! She almost wished they hadn't switched back after all! She considered telling the truth, that it had been Zoe doing all that stuff and not her, so she ought to be the one getting punished, but she doubted it would help. She might even get an extra punishment for misusing her magic the night before! So instead she pouted and fidgeted, trying to find a comfortable position in her full diaper, hoping that Zoe had at least had some fun, since it was her birthday and all, even if Sierra herself was going to have to deal with the consequences of it all.